This is a study of bone mineral on the molecular level with emphasis on the elucidation of the process involved in bone mineralization. The term structure, as used here, includes the identification of the chemical phases present in bone and the molecular arrangement of these chemical constituents. Such techniques as x-ray diffraction, infrared spectroscopy, electron microscopy and electron diffraction will be employed. Studies will be made on normal and diseased bone as well as on analogous synthetic calcium phosphates. In addition, the nature of the mineral in pathological calcification will be investigated.